The southbound lanes of the southern motorway in Auckland are open again after a major upgrade on the Newmarket viaduct was completed ahead of schedule.
An 800 tonne construction gantry has been shifted from a new viaduct to the old southbound lanes.
The southbound motorway was closed at 5pm on Saturday for the work, which was expected to take 24 hours.
Operations Manager Mark Walker says the timeframe allowed for every contingency to be planned for, including bad weather.
Up to 60,000 vehicles normally use the highway on a Sunday. They were being diverted through different parts of the city.
Motorists are being thanked for their patience and co-operation.
The Transport Agency reminds drivers that a reduced speed limit of 70km per hour still applies in both directions across the new and old Newmarket viaducts.
People were earlier advised to stay home to avoid major traffic congestion.
Suburban trains were free during the highway closure.